// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package run implements the ``go run'' command.
package run

import (
	"fmt"
	"os"
	"strings"

	"cmd/go/internal/base"
	"cmd/go/internal/cfg"
	"cmd/go/internal/load"
	"cmd/go/internal/str"
	"cmd/go/internal/work"
)

var CmdRun = &base.Command{
	UsageLine: "run [build flags] [-exec xprog] gofiles... [arguments...]",
	Short:     "compile and run Go program",
	Long: `
Run compiles and runs the main package comprising the named Go source files.
A Go source file is defined to be a file ending in a literal ".go" suffix.

By default, 'go run' runs the compiled binary directly: 'a.out arguments...'.
If the -exec flag is given, 'go run' invokes the binary using xprog:
	'xprog a.out arguments...'.
If the -exec flag is not given, GOOS or GOARCH is different from the system
default, and a program named go_$GOOS_$GOARCH_exec can be found
on the current search path, 'go run' invokes the binary using that program,
for example 'go_nacl_386_exec a.out arguments...'. This allows execution of
cross-compiled programs when a simulator or other execution method is
available.

The exit status of Run is not the exit status of the compiled binary.

For more about build flags, see 'go help build'.

See also: go build.
	`,
}

func init() {
	CmdRun.Run = runRun // break init loop

	work.AddBuildFlags(CmdRun)
	CmdRun.Flag.Var((*base.StringsFlag)(&work.ExecCmd), "exec", "")
}

func printStderr(args ...interface{}) (int, error) {
	return fmt.Fprint(os.Stderr, args...)
}

func runRun(cmd *base.Command, args []string) {
	work.BuildInit()
	var b work.Builder
	b.Init()
	b.Print = printStderr
	i := 0
	for i < len(args) && strings.HasSuffix(args[i], ".go") {
		i++
	}
	files, cmdArgs := args[:i], args[i:]
	if len(files) == 0 {
		base.Fatalf("go run: no go files listed")
	}
	for _, file := range files {
		if strings.HasSuffix(file, "_test.go") {
			// GoFilesPackage is going to assign this to TestGoFiles.
			// Reject since it won't be part of the build.
			base.Fatalf("go run: cannot run *_test.go files (%s)", file)
		}
	}
	p := load.GoFilesPackage(files)
	if p.Error != nil {
		base.Fatalf("%s", p.Error)
	}
	p.Internal.OmitDebug = true
	if len(p.DepsErrors) > 0 {
		// Since these are errors in dependencies,
		// the same error might show up multiple times,
		// once in each package that depends on it.
		// Only print each once.
		printed := map[*load.PackageError]bool{}
		for _, err := range p.DepsErrors {
			if !printed[err] {
				printed[err] = true
				base.Errorf("%s", err)
			}
		}
	}
	base.ExitIfErrors()
	if p.Name != "main" {
		base.Fatalf("go run: cannot run non-main package")
	}
	p.Target = "" // must build - not up to date
	var src string
	if len(p.GoFiles) > 0 {
		src = p.GoFiles[0]
	} else if len(p.CgoFiles) > 0 {
		src = p.CgoFiles[0]
	} else {
		// this case could only happen if the provided source uses cgo
		// while cgo is disabled.
		hint := ""
		if !cfg.BuildContext.CgoEnabled {
			hint = " (cgo is disabled)"
		}
		base.Fatalf("go run: no suitable source files%s", hint)
	}
	p.Internal.ExeName = src[:len(src)-len(".go")] // name temporary executable for first go file
	a1 := b.LinkAction(work.ModeBuild, work.ModeBuild, p)
	a := &work.Action{Mode: "go run", Func: buildRunProgram, Args: cmdArgs, Deps: []*work.Action{a1}}
	b.Do(a)
}

// buildRunProgram is the action for running a binary that has already
// been compiled. We ignore exit status.
func buildRunProgram(b *work.Builder, a *work.Action) error {
	cmdline := str.StringList(work.FindExecCmd(), a.Deps[0].Target, a.Args)
	if cfg.BuildN || cfg.BuildX {
		b.Showcmd("", "%s", strings.Join(cmdline, " "))
		if cfg.BuildN {
			return nil
		}
	}

	base.RunStdin(cmdline)
	return nil
}
